import java.util.*;
class Example2_5 {
	public static void main (String args[]) {
		int start = 0,end,middle;
		int a[] = {12,45,67,89,123,-45,67,20165312};
		int N = a.length;
		for(int  i=0;i<N;i++) {
			for (int j=i+1;j<N;j++) {
				if(a[i] > a[j] ) {
					int t=a[j];
					a[j]=a[i];
					a[i]=t;
				}                                              
			}
		}
		Scanner scanner = new Scanner(System.in);
		System.out.println("输入整数，程序判断该整数是否存在数组中：");
		int number =scanner.nextInt();
		int count = 0;
		end = N;
		middle=(start+end)/2; 
		while(number!=a[middle]) {
			if(number>a[middle])
				start=middle;
			else if (number<a[middle])
				end=middle;
			        middle=(start+end)/2;                                                                                                                                count++;                                                                                                                                             if(count>N/2)                                                                                                                                                break;                                                                                                                               }
		        if(count>N/2)                                                                                      
				System.out.printf("%d不在数组中.\n",number);
			else
				System.out.printf("%d在数组中.\n",number);
	}
}
